Method of making tappets



Sept. 18, 1934.

H. J. LONG 1,973,855

METHOD OF MAKING TAPPETS Filed Oct. 23. 1930 4/ mun mum Patented Sept.18, 1934 LINETED STATES PATENT OFFICE eral Motors Corporation, Detroit,

poraticn of Delaware Mich., a cor-- Application October 23, 1930, SerialNo.- 490,616

2 Claims.

This invention relates to tappets such as are used on engines totransmit the motion of the cams to the valves.

An object of the invention is to make a tappet structurally superior totappets as heretofore made.

A further object of the invention is to reduce the expense of makingsuch superior tappets.

The invention relates more particularly to that kind of tappet having asteel shank, preferably hollow, with a cast iron head secured to theshank, and has for its object an improvement in the structure of such atappet and an improvement in the process of making it.

More specifically the invention provides for the use of an annular steelstamping together with a hollow steel shank of substantially uniformdiameter throughout and a cast iron head. In connection with such atappet another object of this invention relates to the specificarrangement of these parts and the process of welding them together.

Other objects and advantages will appear from the followingspecification and the accompanying drawing.

In the drawing- Fig. 1 is an end view of an engine, partly in section,showing the tappet and the parts with which it is associated.

Fig. 2 is a perspective of parts constituting the tappet in disassembledrelation.

Fig. 3 is a view partly in elevation and partly in section of the tappetwith its parts assembled for the welding operation.

Fig. 4 is a view similar to Fig. 3 showing the welded tappet.

In the drawing numeral 5 is used to designate an engine having a head 7.At 9 is seen the piston reciprocably mounted in a cylinder 11. At 13 isshown one of the usual spark plugs,- and the numeral 15 represents oneof the valves. The valve is normally held seated by a spring 17, and itsstem 19 is engaged and reciprocated by an adjustable abutment 21threaded to the end 23 of the tappet designated, as a whole, by numeral25. The tappet is slidably mounted in a guide 28 and is actuated by aconventional cam 30.

The tappet 25 is formed by uniting three separate parts. There is atubular stem shank 27, a cast iron cam-engaging head 29, and an annularsteel stamping 31. The steel shank is to be internally threaded at oneend for adjustably securing the abutment as explained above.

Figs. 3 and 4 show the tappet before the threads are provided. At itsother end the shank is slightly reduced in diameter forming a shoulder33. It will be observed that there is no integral enlarged head as iscommonly provided, it beingobvious that the unheaded shankis moreeconomical in production than the shank with an integral enlarged head.The extremity of the reduced end of the shank is chamfered both insideand outside as at 35. The steel stamping snugly fits over the reducedportion of the shank and engages the shoulder 33. Its thickness is lessthan 5 V the axial length of the reduced portion of the shank, so thatthe chamfered extremity extends beyond the plane of the stamping.Peripherally the stamping is distorted from the plane of its innerregion, such distortion turning up an edge indicated on the drawing bynumeral 37. This edge 3'? lies substantially in the plane of theextremity of the tubular shank. The cast iron head 29 is a simple dischaving a radius corresponding substantially with, or but slightlygreater than that of the stamping. The head is positioned concentricallywith the shank and stamping, and when so positioned engages thechamfered end of the shank and the edge 37 of the stamping.

At 39 is a support for the shank and the stamping when the latter is inposition as shown. At 41 is a member mounted movably in the axis of theshank and is arranged to press the head 29 in the direction of the saidaxis. Preferably the member 41 may be provided with tongues as shown toaccurately position the head 29. The members 39 and 41 may serve aselectrodes for the welding current. As is well known the cast iron has alower melting temperature than the steel, and by making those regions ofthe steel which engage the cast iron of reduced dimensions, as at 35 and37, there is a tendency to equalize the melting action of the twomembers to be welded together. Under the influence of pressure from part41 and the heat from the current, the extremity of the shank is weldedboth to the head 29 and to the inner periphery of the stamping. Theouter periphery of the stamping is also welded to the outer periphery ofthe disc-shaped cast iron head. As a result of this arrangement the castiron head does not have an unsupported overhang from the tubular shankas in some former constructions, but is supported by the steel stampingthroughout substantially its whole surface, which stamping is itselfwelded to the shank. Added support is thus given the cast iron head asin the case of the more expensive integrally headed steel shanks.

It will be seen that the shank itself is less ex pensive to manufacture,that the disc or head 29 11C is simple and comparatively inexpensive,and requiring no machining, may be made from any non-machinable castiron. The reinforcing back or support is an inexpensive stamping. Theparts, when assembled, are permanently welded together by a singlewelding operation. There is thus made from parts which are themselvesinexpensive to manufacture a composite tappet which has the best knownkind of cam-engaging head, the lightest and strongest shank, and thehead is not only securely welded to the shank but by the single weldingoperation there is also secured both to the shank and to the head thedisc of steel which provides as effective a supporting back for the castiron head as is obtained in-the case of the more expensive constructioninvolving a shank with an integral enlarged end portion.

It should be explained that the expression substantially uniformdiameter as applied to the shank is intended to difierentiate from ashank with-an end materially enlarged radially-to form a cam-engaginghead or to support such a head, the word substantially being used toaccurately describe this shank which does have its end slightly reducedto-receive and support the stamping.

I claim:

1. The process of making a tappet comprising: preforming a tubular shankof steel; preforming an annular steel stamping; preforming a discshapedpart of cast iron; assembling said stamping about the end of said shankand said disc upon said stamping and end of said shank and thereafterwelding said parts together by welding together the peripheral regionsof the steel stamping and the cast iron disc and by welding the shank tothe disc and stamping.

2. The process of making a tappet comprising preforming a tubular shankof steel with a reduced end; preforming an annular steel stamping with aperipheral distortion to produce an axially projecting circular edge,preforming a disc of cast iron, assembling said stamping about the endof said shank, assembling said disc upon the reduced end of said shankand upon said circular edge and thereafter welding said parts togetherby welding together the peripheral regions of the steel stamping and thecast iron disc and by welding the shank to the disc and stamping.

HENRY J. LONG.

